Non-clogging pumps



Dec m, 3.9% v. D. SWEENEY ETAL 3529?@473 NON-'CLOGGING PUMPS Filed Feb, e, 1965 "1' ATTORNEYS United States Patent O 3,291,473 NN-CLOGGING PUMPS Victor D. Sweeney, Euclid, and Walter U. Kaji, Chagrin Falls, Ohio, assignors to Metal Pumping Services, Inc., Cleveland, hio, a corporation of Ohio Filed Feb. 6, 1963, Ser. No. 256,634 14 Claims. (Cl. 266-38) This invention relates to centrifugal pumps of the type having an inlet opening into a housing containing a rotary impeller. More particularly, the invention relates to improvements in such pumps by which the entry of large solid particles and/ or agglomerates of solid and/ or semisolid materials into the pump through the inlet opening is limited as may be required to prevent clogging of the passageways therein, jamming of the pump parts so as to prevent operative movement of the impeller, and damage to the pump from such clogging or jamming.

The invention is especially applicable to submersible pumps, i.e., pumps designed to be submerged in a reservoir of liquid for drawing the liquid directly from the reservoir into a pumping chamber. However, the principle of the invention is not limited to its use. in such an environment. For example, the pump itself may be disposed entirely outside the reservoir with its inlet opening being defined by a passageway through the reservoir wall that leads into the pumping chamber of the pump.

The invention has been applied with particular success to pumps for molten metal where the molten metal to be pumped is contaminated by floating, entrained, or settled solid and/ or semi-solid material such as fluxes, slags, unmelted metals, dross, refractory fragments, and other solid or agglomerated foreign matter. However, as will become more apparent, the invention is equally applicable to the pumping of any kind of hot or cold liquids containing solid or agglomerated matter which might otherwise damage or interfere with the proper operation of pumps of the broad mechanical classification first mentioned above.

As has been indicated above, the principal object of the invention is to provide centrifugal pump structures of the types described with improved means for preventing clogging of the passages therein, and/ or jamming of the pump parts, and/ or damage to the pumps.

More specifically, itis an object of the invention to provide such pumps where the means for preventing such clogging, jamming, and damage has a self-cleaning action not possessed by simple strainers or sieves heretofore used for the same and similar purposes.

A further object of the invention is to accomplish the foregoing objects in a simple, inexpensive, and reliable manner.

A still more specific object of the invention is to accomplish all of the foregoing objectives using mechanical parts and operating principles adaptable to pumps made largely or entirely out of relatively fragile, brittle, refractory materials that are resistant to attack and disintegration when immersed and operated in molten metals, particularly in metals having melting temperatures above those at which the common structural metals retain any significant or prolonged structural value.

The invention by which the foregoing objectives are achieved involves the addition of a so-called deflector disk to a pump of the class described, the disk being mounted for rotation so that its periphery cooperates with the inlet opening into the pump body to define an entrance passageway of suitable dimensions for restricting the admission of solid and semi-solid materials. The spacing of the deilector disk outwardly from the inlet opening or radially inwardly from the cylindrical wall of the bore determines the size of solid particles or agglomerates of solid and semi-solid materials that can pass into the pump 3,291,473 Patented Dec. 13, 1966 ICC chamber. This spacing is selected in View of the sizes of such particles and agglomerates that can pass into and through the pump without clogging or damaging it.

Preferably, as in the exemplary structures disclosed herein, the pump impeller shaft extends through the inlet opening and carries the deflector disk, although other schemes for mounting and rotating the deflector disk may be employed. The deflector disk may be mounted for axial rotation, preferably in axial alignment with an inlet opening into the pump chamber, the diameter of the disk being substantially as great as or greater than the diameter of the inlet opening and the disk being spaced axially outwardly from the opening so as to provide an annular opening of restricted width for admitting liquid to be pumped. Alternately the disk may be recessed within a cylindrical inlet passageway communicating with the pumping chamber. In this embodiment the periphery of the disk is spaced radially inwardly from the wall of the passageway, thereby providing an annular opening of restricted width for admitting liquid to be pumped.

In the case of solid particles that are too large to move freely between the periphery of the rotating defiector disk and the stationary periphery of the inlet opening, the movement of the disk relative to the pump chamber housing acts to throw such particles aside and aids in preventing any accumulation of such particles about the inlet opening. This minimizes clogging of the opening while preventing particles of excessive size from entering the pump chamber. Agglomerates of solid and/ or semi-solid materials are similarly defiected by the same relative movement, or are broken up so that they can freely flow into and through the pump.

Although the addition of the deflector disk necessarily also has a restricting effect upon the flow of liquid into the pump chamber, this effect is not normally so pronounced as to be serious. In many instances, the inlet opening in the pump housing is larger than necessary, so that the restriction caused by addition of the deflector disk is immaterial. In other instances, the overall fiow rate is not actually reduced in practice by addition of the deflector disk because the avoidance of clogging offsets such reduction in the effective inlet port area as is caused by addition of the deflector disk.

The foregoing and additional objects, features, and advantages of the invention will be more fully understood and appreciated from the following detailed description of illustrative embodiments of the invention and from the illustrations thereof in the accompanying drawings.

In the drawings:

FIG. l is an elevational view, with parts in cross section, of a pump modified according to the present invention and submerged in a molten metal bath environment;

FIG. 2 is an enlarged, sectional view taken on line 2-2 of FIG. 1;

FIG. 3 is a further enlarged sectional View taken on line 3-3 of FIG. 2;

FIG. 4 is a sectional view of another form of the general type of pump shown in FIG. 1, embodying another application of the present invention; and

FIG. 5 is a sectional view of a different kind of pump modified according to the present invention.

Referring to FIG. l, there is shown a pumping apparatus 10 of the type disclosed and claimed in prior Patent No. 3,048,384, granted August 7, 1962, but modified according to the present invention. The apparatus 10 is shown partially submerged in a bath of molten metal 12 contained in a suitable container 14.

The submerged portion of the apparatus (more easily understood by also referring to FIGS. 2 and 3) includes a pump foot body 16, a cylindrical bore 18 extending axially and vertically through the foot body 16 for receiving an impeller and defining an inlet opening, and an 3 impeller 20 threadedly mounted on a coaxially disposed shaft 22 for coaxial rotation within the bore 18. The impeller 20 is generally in the form of a cup that is inverted for drawing molten metal upwardly into the cup from below the foot body.

Extending through the threaded mounting of the irnpeller 20 and beyond the plane defined by the bottom surface 23 of the foot body 16 is a portion 24 of the shaft 22 having a reduced diameter. A deflector disk 26, threadedly mounted on this portion 24 of the shaft 22, is spaced a predetermined distance S from the plane delined by the bottom surface 23 of the body 16. This distance is predetermined by the size of the particulate or agglomerate material to be deected. The defiector disk 26 rotates simultaneously with the impeller 20, both being supported and driven by the shaft 22.

In order to be most effective in defiecting solid particles and the like, the disk 26 is preferably at least substantially radially coextensive with the bore 18, as shown in FIGS. 1 and 3, illustrating a preferred minimum size of deflector disk for this embodiment of the invention. The deflector disk 26 may be substantially greater in diameter than the bore 18 of the foot body, as shown in the embodiment illustrated in FIG. 5, the deecting function being enhanced as the disk diameter is increased, but with a correspondingly increased resistance to the flow of molten metal past the disk to the impeller.

As an alternative embodiment, however, the defiector disk 26 may be recessed at least partially and coaxially within the bore of the foot body 16, as shown in the embodiment of FIG. 4 and hereinafter described. By employing a foot body having a somewhat greater depth than the foot body 16 shown in FIG. 1, a defiector disk of reduced diameter may be recessed in the bottom of the foot body. The entrance restriction in the latter case is determined by the selected spacing of the perimeter of the deflector disk radially inwardly from the wall of the inlet opening. Similarly, the location of the deflector disk 26 axially outwardly beyond the plane of the foot body that defines the inlet opening, as shown in FIG. 1, is applicable to the apparatus of FIG. 4 having an upwardly directed inlet opening.

An offset bore 28 extends partially downwardly through the body providing communication between an outlet opening 30 and a discharging conduit 32. A volute member 33 (FIG. 2) is positioned in the middle portion of the bore and is supported in such position by a bearing ring 33a defining part of the bore 18, as indicated in FIG. 1.

The pump impeller 20 (better understood by referring to FIGS. 2 and 3) is generally cylindrical in form and has a depending skirt portion 34 which surrounds an axially extending internal cavity or bore 35. Six passages 36 extend through the skirt portion of the impeller 20 and communicate with the impeller bore 35. The passages 36 are preferably of constant cross section and slant backwardly from their outer ends with respect to the direction of rotation of the impeller. The impeller has a second, axially extending bore 38 in which the imf peller threadedly receives the pump shaft 22.

Heretofore, it has generally been considered desirable when pumping molten aluminum, for example, to draw the molten metal downwardly into the pump from a level in the bath which is above the foot body, as shown in FIG. 4 and hereinafter more fully described. With such an arrangement, heavy slags and dross, which tend to sink to the bottom of molten metal baths of such low specific gravity, are less apt to be drawn into the inlet opening of the pump. On the `other hand, larger diameter pump shafts 22 may be connected to support and drive the impeller 20 when the impeller opens downwardly, as shown in FIG. 1, for drawing molten metal upwardly from below the foot body, without unduly obstructing the flow of molten metal into the impeller. This contributes to the ruggedness and durability of the construction. The defiector disk 26 generally ecounters less resistance to rotation than the impeller 20 and may be supported with adequate strength on a shaft of smaller diameter, such as the reduced diameter shaft portion 24 in FIG. 1. The smaller diameter of the shaft portion 24 provides less obstruction to the ow of molten metal into the impeller while providing adequate support for the deflector disk 26.

It has now been found that the employment of the deflector disk 26 with the type of pump shown in FIG. 1, which draws molten metal upwardly into the impeller from below the foot body, permits this type of pump to be employed in molten aluminum baths with a greatly reduced tendency for drawing large solid particles and agglomerates into the pump. This improvement is such that the more rugged construction of the type of pump shown in FIG. 1 is now preferred for use in light metal baths, such as aluminum baths, instead of the previously preferred but more fragile construction of the apparatus of FIG. 4.

In some instances, however, it may still be desired to employ the apparatus arrangement of FIG. 4 in which the impeller opens upwardly and draws metal downwardly into the pump from a level above the foot body. In this case, the apparatus of FIG. 1 may readily be modified to provide the arrangement` shown in FIG. 4 by simply removing the impeller 20 and shaft 22 of FIG. 1 and substituting the modified, relatively inverted impeller 40 and the modified shaft 42 that are shown in FIG. 4. This may be done using the same foot body 16 shown in FIG. 1 with the same deflector disk 26 mounted on the modified shaft and spaced axially above the foot body 16 by the same distance S, and with the reduced diameter end portion of the shaft 42 threaded into the inverted impeller 40.

The impeller 40 is similar to the impeller 20, but is in an inverted position with respect to the impeller 20, .e., the inlet opening formed by the bore 18 extends upwardly, rather than downwardly as when the impeller 20 is used. However, the radially extending passages 43 which communicate with the bore 18 of the impeller 40 again slant backwardly with respect to the direction of rotation of the impeller, similarly to the passages 36 of the impeller 20, rather than slanting in the opposite direction, as would be the case if the impeller 20 were merely inverted.

For the purpose of illustrating a further variation of the present invention, the apparatus of FIG. 4 is shown with a modified foot body 45 of greater vertical thickness than the foot body 16 of FIG. 1, and with the defiector disk 44 of reduced diameter recessed within a bore 48 of the foot body 45 and spaced radially inwardly from the wall of the bore by a selected distance S.

The shaft 42 connecting the impeller 40 with the motor is somewhat shorter in overall length than the shaft 22 employed with the impeller 20. This is due to the fact that the disk 44 is threadedly mounted on the shaft above the impeller and therefore does not have to extend beyond the bottom surface of the foot body.

The embodiment of the invention illustrated in FIGS. 1-3, the above-described modifications thereof, and the further modification illustrated in FIG. 4 are all adapted to be dismantled without removing the defiector disk from the shaft 22 (FIGS. 1 and 3) or from the shaft 42 (FIG. 4). This is done by withdrawing the pump from the molten metal bath, disconnecting the shaft 22 or 42 from its drive mechanism, and dropping the shaft and its associated impeller and deflector disk downwardly relative to the foot body 16 or 45. Initial assembly is performed in the reverse manner. The only exception would reside in the case Where the deflector disk is mounted above the foot body in association with an upwardly directed inlet opening and the deflector disk is larger in diameter than the inlet opening. In this case, assembly of the shaft and its associated impeller and deflector disk with the foot body must be performed while the drive mechanism thereabove is removed to permit vertical insertion and withdrawal of the shaft with its associated impeller and deiiector disk.

Depending upon the particular type of molten metal to be pumped, the character and relative specific gravity of the solid particles and agglomerates to be deflected, and the particular environment in which the invention is to be used, one or another of the abovedescribed embodiments of the invention may be preferred. In all of those embodiments, the operation is essentially the same as regards the function performed by the particular deflector disk employed. In each case, the molten metal Hows around the deector disk and into the foot body through the inlet opening defined by the vertical bore therethrough, while large solid particles and agglomerates are held back and deected by the rotating deilector disk. The molten metal then passes into the cavity of the impeller and radially outwardly through the passages 36 (FIG. 3) or 43 (FIG 4), laterally through the outlet opening 30 by the volute member 33 (FIG. 2) and through the discharging conduit 32 for disposition in any desired manner.

The portions of the above-described molten metal pump which are exposed to contact with the molten metal or which are immersed in the molten metal bath, such as the defiector disk, the pump foot body, the volute member, the bearing ring, the impeller, the shaft, and the conduit, are all formed of a suitable material which will resist corrosive attack by the molten metal. These parts may be fabricated from a non-metallic refractory material having high resistance to attack by the molten metal, and which will not introduce contaminants into the molten metal. For example, structural carbonaceous and siliceous refractory materials, such as graphite, graphitized carbon, clay-bonded graphite, carbon-bonded graphite, silicon carbides, aluminum silicates, and other bonded refractory mixtures containing such materials, may be successfully employed. Where graphite is employed as the structural material, it is of advantage to make at least the peripheral portion of the deflector disk from silicon carbide for greater abrasion resistance.

It is to be understood that the principles of the present invention have application to pumps used with liquids other than those existing only at high temperatures. The only consideration in applying the principles of the present invention is that there be a problem with clogging or jamming of the passageways through the pump from particulate or agglomerate materials.

Pumps used in conveying low temperature liquids such as the cryogenics, or liquids at room temperature, or even liquids at temperatures up to about 500 C., may advantageously be modified according to the present invention.

Referring to FIG. 5, there is shown a pump made of metal and designed to be used with liquids at temperatures ranging from room temperature up to about 750 C. or so, depending on the high temperature strength of the structural metal employed, particularly for the pumping of a large volume of a liquid or molten chemical. The structure of this pump generally comprises a two-component cylindrical body 50 having a stationary section 52 integral with a U-cross sectioned support 54 and a removable section 56. The cylindrical body 50 includes a pump chamber 58 and an upper inlet chamber 60.` The upper inlet chamber 60 is provided with inlet apertures 62. Axially disposed at the top and bottom of the pump chamber are an upper inlet 64 and a lower inlet 66, respectively. An impeller 68 is rotatably mounted within the pump chamber 58 on a rotatably, pendently supported shaft 72. The shaft 72 extends downwardly between the walls of the U-shaped support 52, through a bearing 74, through both of the inlets 64 and 66, and slightly beyond the bottom surface 7 6 of the pump chamber 53. In this particular embodiment the impeller comprises outwardly extending, fiat surfaced vanes 82 integral with a radially extending, reinforcing web 84.

An upper deector disk 78 and a lower deector disk 80 are mounted axially outwardly in spaced relationship from the upper inlet 64 and the lower inlet 66, respectively. As the shaft 72 rotates to drive the impeller 68, both the upper disk 7S and the lower disk 80 are simultaneously driven therewith. The axial spacing S between the surfaces of the disks facing the inlets and the outer surfaces 76 and 82 of the pump chamber 58 is predetermined in the same manner as above. Only matter passable through spacing S enters outlet S1 extending outwardly and upwardly from the pump chamber 58.

It should be noted that the deflector disks 78 and 80 have a diameter considerably in excess of the inlet openings 64 and 66. The critical distance S in this case is, as before, the distance from the periphery of the inlet openings to the disks. The ultimate diameter of the disks is not critical and is only determined by practicality, there being no advantage in greatly increasing their diameter.

Since, as pointed out above, various modifications may be made within the scope of the invention, the invention is not intended lto be limited to the particular pump structures described in detail herein, except as may be required by the appended claims.

What is claimed is:

1. In a pump comprising a hollow body defining an inlet opening and an outlet opening and a chamber providing liquid communication between said openings, and pumping means cooperating with said chamber and openings to draw a liquid stream into said inlet opening and through said chamber and to discharge the same through said outlet opening, the improvement in said combination wherein an imperforate deflector disk is mounted for rotation about an axis of said inlet opening, the disk and the periphery of said inlet opening being spaced apart by a distance less than the maximum d'imension of solid particles capable of passing into and through said pump with said liquid stream, said disk being substantially normal to said axis.

2. In a pump as defined in claim l, the improvement wherein there are at least two inlet openings and a corresponding number of deflector disks respectively associated with the inlet openings as defined in claim 1.

3. In a pump comprising a hollow body dening an inlet opening and an outlet opening and a chamber providing liquid communication between said openings, and pumping means cooperating with said chamber and openings to draw a liquid stream into said inlet opening and through said chamber and to discharge the same through said outlet opening; the improvement in said combination wherein an imperforate deector disk is mounted for rotation about an axis of said inlet opening, said disk and the periphery of said inlet opening being spaced apart by a distance less than the maximum dimension of solid particles capable of passing into and through said pump with said liquid stream, said deflector disk being located axially outwardly beyond said inlet opening and being substantially normal to said axis.

4. In a pump comprising a hollow body defining an inlet opening and an outlet opening and a chamber providing liquid communication between said openings, and pumping means cooperating with said chamber and openings to draw a liquid stream into said inlet opening and through said chamber and to discharge the same through said outlet opening, the improvement in said combination wherein an imperforate deiiector disk is mounted for rotation about an axis of said inlet opening, said disk and the periphery of said inlet opening being spaced apart by a distance less than the maximum dimension of solid particles capable of passing into and through said pump with said liquid stream, said deilector disk being located within said inlet opening and being substantially normal to said axis.

5. In a pump comprising a hollow body dening an inlet opening and an outlet opening and a chamber providing liquid communication between said openings, and pumping means cooperating with said chamber and openings to draw a liquid stream into said inlet opening and through said chamber and to discharge the same through said outlet opening, the improvement in said combination wherein the outside surface of said body surrounding the inlet opening is substantially at and generally defines a plane, and an imperforate deflector disk is spaced axially outwardly from said inlet opening and has a diameter at least substantially as great as the greatest span of said inlet opening, said disk being mounted to rotate substantially parallel to said plane about an axis substantially perpendicular to said plane in substantially axial alignment with said opening, said disk and the periphery of said inlet opening being spaced apart by a distance less than the maximum dimension of solid particles capable of passing into and through said pump with said liquid stream, whereby particles or agglomerates of solid and semi-solid materials larger than the spacing of said disk from said plane are restricted from passing through said inlet opening.

6. In a pump as defined in claim 5, the improvement wherein there are at least two inlet openings and a corresponding number of deector disks respectively associated with the inlet openings as dened in claim 5, whereby said particles or agglomerates of solid and semi-solid materials larger than the spacing of said disk from said plane are restricted from passing through all of said inlet openings.

7. In a pump comprising a hollow body dening an inlet opening and an outlet opening and a chamber providing liquid communicattion between said openings, and an impeller mounted on a shaft for rotation within said chamber for drawing liquid into said inlet opening and through said chamber and discharging the liquid from said outlet opening, the improvement in said combination wherein the outer surface f said body surrounding said inlet opening is substantially flat and generally denes a plane, and an imperforate detlector disk is spaced axially outwardly from said inlet opening and has a diameter at least substantially as great as the greatest span of said inlet opening, said disk and the periphery of said inlet opening being spaced apart by a distance less than the maximum dimension of solid particles capable of passing into and through said pump with said liquid stream, said disk being mounted to rotate substantially parallel to said plane about an axis substantially perpendicular to said plane in substantially axial alignment with said opening, whereby particles or agglomerates of solid and semi-solid materials larger than the spacing of said disk from said plane are restricted from passing through said inlet opening.

8. The improved combination of claim 7 wherein said disk is also mounted on said shaft.

9. In a pump comprising the combination of a hollow body having an inlet opening and an outlet opening and dening a cylindrical chamber providing liquid communication between said openings, and an impeller rotatably mounted on a shaft within said chamber for drawing liquid into said inlet opening and through said chamber and to discharge the same through said outlet opening, the improvement in said combination wherein the surface of said body surrounding said inlet opening is substantially flat and generally defines a plane perpendicular to said axis of rotation, and an imperforate deflector disk is mounted on and is normal to said shaft and is spaced axially outwardly from said opening, said disk and the periphery of said inlet opening being spaced apart by a distance less than the maximum dimension of solid particles capable of passing into and through said pump with said liquid stream, said disk being at least substantially radially coextensive with said opening whereby said particles or agglomerates of solid and semi-solid materials larger than the spacing of said disk from said plane are restricted from passing through said inlet opening.

10. In a pump comprising the combination of a hollow body having an inlet opening and an outlet opening and defining a cylindrical chamber providing liquid communication between said openings, and an impeller rotatably mounted on a shaft within said chamber for drawing liquid into said inlet opening and through said chamber and to discharge the same through said outlet opening, the improvement in said combination wherein an imperforate deector disk is mounted on said shaft substantially coaxially with the said chamber, the perimeter of said disk being spaced radially inwardly from the wall of said cylindrical chamber, said disk being substantially normal to said shaft, the space between the wall of the cylindrical chamber and the perimeter of the disk being less than the maximum dimension of solid particles capable of passing into and through said pump with said liquid stream, whereby said particles or agglomerates of solid and semi-solid materials larger than the spacing of said disk from said walls are restricted from passing through said inlet opening.

11. In a pump for molten metal comprising the combination of:

(a) a lower foot body in the form of a refractory slab adapted to be immersed in molten metal or other liquid of high temperature, having upper and lower faces and defining a pump chamber therein and having coaxial upper and lower vertical bores of the same diameter extending into the pump chamber through said upper and lower faces of the slab, respectively;

(b) a refractory centrifugal impeller body having a periphery of cylindrical contour and an inlet that opens axially into one end only thereof, said impeller body projecting into said pump chamber and being journaled in said bores; and

(c) a vertically disposed refractory pump shaft connected in coaxial driving relationship with said impeller body;

the improvement in said combination wherein an imperforate deector disk is mounted for rotation about an axis of said inlet opening, said disk and the periphery of said inlet opening being spaced apart by a distance less than the maximum dimension of solid particles capable of passing into and through said pump with said liquid stream, and said disk being substantially normal to said axis.

12. In a pump as defined in claim 11, the improvement wherein there are at least two inlet openings and a corresponding number of deflector disks respectively associated with the inlet openings as defined in claim 11.

13. In a pump for molten metal comprising the combination of:

(a) a lower foot body in the form of a refractory slab adapted to be immersed in molten metal or other liquid of high temperature, having upper and lower faces and defining a pump chamber therein and having coaxial upper and lower vertical bores of the same diameter extending into the pump chamber through said upper and lower faces of the slab, respectively;

(b) a refractory centrifugal impeller body having a periphery of cylindrical contour and an inlet that opens axially into one end only thereof, said impeller body projecting into said pump chamber and being journalled in said bores; and

(c) a vertically disposed refractory pump shaft connected in coaxial driving relationship with said irnpeller body;

the improvement in said combination wherein an imperforate deector disk is mounted for rotation about an axis of said inlet opening, said disk and the periphery of said inlet opening being spaced anart by a distance less than the maximum dimension of solid particles capable of passing into and through said Pump With said liquid stream, said dellector disk being located axially outwardly beyond said inlet opening and being substantially normal to said shaft.

14. In a pump for molten metal comprising the combination of:

(a) a lower foot body in the form of a refractory slab adapted to be immersed in molten metal or other liquid of high temperature, having upper and lower faces and defining a pump chamber therein, and having coaxial upper and lower axially vertical bores of the same diameter extending into the pump chamber through said upper and lower faces of the slab, respectively;

(b) a refractory centrifugal impeller body having a periphery of cylindrical contour and an inlet that opens axially into one end only thereof, said impeller body projecting into said pump chamber and being journalled in said bores; and

(c) a vertically disposed refractory pump shaft connected in coaxial driving relationship with said impeller body;

the improvement in said combination wherein the bottom face of said slab is flat and defines a plane perpendicular to the axis of said bores and wherein said shaft extends beyond said plane with an imperforate disk mounted coaxially thereon and spaced outwardly from said plane, said disk being normal to said shaft, the space between said plane and said disk being less than the maximum dimension of solid particles capable of passing into and through said pump with said liquid stream, the diameter of said disk being slightly less than the diameter of said portion permitting withdrawal of the shaft mounted disk through said vertical portion, whereby said disk acts to restrict particles and agglomerates of solid and semi-solid materials larger than the spacing of said disk from passing through said pump.

References Cited by the Examiner UNITED STATES PATENTS 1,037,659 9/1912 Rembert 103-111 2,714,354 8/1955 Farrand 103-111.1 2,775,348 12/1956 Williams 103-1 11.1 2,918,876 12/1959 Howe 103-111.1 2,948,524 8/1960 Sweeney et al 266-38 3,048,384 8/1962 Sweeney et al 266-38 FOREIGN PATENTS 149,811 4/ 1955 Sweden.

JOHN F. CAMPBELL, Primary Examiner. P. M. COHEN, Assistant Examiner. 

1. IN A PUMP COMPRISING A HOLLOW BODY DEFINING AN INLET OPENING AND AN OUTLET OPENING AND A CHAMBER PROVIDING LIQUID COMMUNICATION BETWEEN SAID OPENINGS, AND PUMPING MEANS COOPERATING WITH SAID CHAMBER AND OPENINGS TO DRAW A LIQUID STREAM INTO SAID INLET OPENING AND THROUGH SAID CHAMBER AND TO DISCHARGE THE SAME THROUGH SAID OUTLET OPENING, THE IMPROVEMENT IN SAID COMBINATION WHEREIN AN IMPERFORATE DEFLECTOR DISK IS MOUNTED FOR ROTATION ABOUT AN AXIS OF SAID INLET OPENING, THE DISK AND THE PERIPHERY OF SAID INLET OPENING BEING SPACED APART BY A DISTANCE LESS THAN THE MAXIMUM DIMENSION OF SOLID PARTICLES CAPABLE OF PASSING INTO AND THROUGH SAID PUMP WITH SAID LIQUID STREAM, SAID DISK BEING SUBSTANTIALLY NORMAL TO SAID AXIS.
 14. IN A PUMP FOR MOLTEN METAL COMPRISING THE COMBINATION OF: (A) A LOWER FOOT BODY IN THE FORM OF A REFRACTORY SLAB ADAPTED TO BE IMMERSED IN MOLTEN METAL OR OTHER LIQUID OF HIGH TEMPERATURE, HAVING UPPER AND LOWER FACES AND DEFINING A PUMP CHAMBER THEREIN, AND HAVING COAXIAL UPPER AND LOWER AXIALLY VERTICAL BORES OF THE SAME DIAMETER EXTENDING INTO THE PUMP CHAMBER THROUGH SAID UPPER AND LOWER FACES OF THE SLAB, RESPECTIVELY; (B) A REFRACTORY CENTRIFUGAL IMPELLER BODY HAVING A PERIPHERY OF CYLINDRICAL CONTOUR AND AN INLET THAT OPENS AXIALLY INTO END ONLY THEREOF, SAID IMPELLER BODY PROJECTING INTO SAID PUMP CHAMBER AND BEING JOURNALLED IN SAID BORES; AND (C) A VERTICALLY DISPOSED REFRACTORY PUMP SHAFT CONNECTED IN COAXIAL DRIVING RELATIONSHIP WITH SAID IMPELLER BODY; THE IMPROVEMENT IN SAID COMBINATION WHEREIN THE BOTTOM FACE OF SAID SLAB IS FLAT AND DEFINES A PLANE PERPENDICULAR TO THE AXIS OF SAID BORES AND WHEREIN SAID SHAFT EXTENDS BEYOND SAID PLANE WITH AN IMPERFORATE DISK MOUNTED COAXIALLY THEREON AND SPACED OUTWARDLY FROM SAID PLANE, SAID DISK BEING NORMAL TO SAID SHAFT, THE SPACE BETWEEN SAID PLANE AND SAID DISK BEING LESS THAN THE MAXIMUM DIMENSION OF SOLID PARTICLES CAPABLE OF PASSING INTO AND THROUGH SAID PUMP WITH SAID LIQUID STREAM, THE DIAMETER OF SAID DISK BEING SLIGHTLY LESS THAN THE DIAMETER OF SAID PORTION PERMITTING WITHDRAWAL OF THE SHAFT MOUNTED DISK THROUGH SAID VERTICAL PORTION, WHEREBY SAID DISK ACTS TO RESTRICT PARTICLES AND AGGLOMERATES OF SOLID AND SEMI-SOLID MATERIALS LARGER THAN THE SPACING OF SAID DISK FROM PASSING THROUGH SAID PUMP. 